shure 849

i recently stumbled upon 2 Shure 849's, a friend of mine was cleaning out his churches extra closets and found a set of them and gave them to me. i'm having some trouble though finding out any information on the 849. i know the general stuff...assuming they are unidirectional cardoid condensers. i guess for the heck of it i want to know more about this mic like year they were common and how popular or in use they are...any help?